


Grimm Breeding

by FestivalGrey



Category: RWBY
Genre: Bestiality, Breeding, Consensual, Consensual Sex, F/M, Immobility, Impregnation, Knotting, Lactation, Lactation Kink, Maternal Instinct, Mating Cycles/In Heat, Oral Sex, Pregnancy, Pregnancy Kink, Pregnant Sex, So pregnant you can't move, Teratophilia, Vaginal Sex, carrying lots of baby monsters, monster fucking
Language: English
Status: In-Progress
Published: 2019-11-28
Updated: 2019-11-28
Packaged: 2021-02-26 16:27:48
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,167
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21591262
Author URL: https://archiveofourown.org/users/FestivalGrey/pseuds/FestivalGrey
Summary: Across Remnant, the Grimm are falling. Salem alights on a plan to repopulate their numbers—one that uses the wombs of her own willing subordinates as the means to do so.Written for an anonymous user. Is planned to encompass multiple characters; tags and relationships will be updated as more chapters are written.
Relationships: Cinder Fall/Creatures of Grimm
Comments: 10
Kudos: 131





	Grimm Breeding

Salem, leader of the conspiracy against Remnant, was not pleased. The immortal woman’s eyes—dark and glistening like slicks of oil—shimmered with anger, and she drummed her ashen fingertips on the table.

“Ozpin’s brats are thinning our numbers at an unacceptable rate,” she said, her voice flat and icy. “The Faunus of Menagerie have taken the fight as well, and the kingdoms are rallying. Huntsmen and Huntresses across the map are making a strike against our Grimm.” She slowly placed her palms down on the table, and a thin smile touched her lips. “Luckily for us, I have a plan—one that involves the three of you.”

Cinder Fall shifted her head to meet the eyes of the others that were in the room with her. Salem had forgone summoning her usual coterie of allies and stooges. Instead, there were only three who were meeting with her today: the silent assassin named Neopolitan, and Cinder’s own subordinate, Emerald Sustrai. Each of the other two women touched Cinder’s gaze, and unspoken dialogue passed between them in the way their eyes met, squinting in query and raising their eyebrows quizzically.

“Confused, are we?” Salem said, an amused note creeping into her voice. “Don’t be. Follow, and I will enlighten you.” She rose from the long table they were gathered at and glided out of the room. Each of the three women followed on her heels.

“Naturally, the Grimm numbers need replenishment,” Salem lectured as they walked. “The pools of darkness which spawn them help, of course, but I have long wondered if there might not be a more… _naturalistic_ way of propagating them.”

Emerald fell in beside Cinder. “What does she mean?” she asked in a low voice.

“If you have a question, you should ask it _directly,_ Ms. Sustrai,” Salem said, prompting a worried look to crawl onto Emerald’s face. “But perhaps I can illustrate to you what exactly it is that I ‘mean.’” By now they were at a high window overlooking fields where the Grimm prowled. Salem turned to face them, her back to the window, and the expanse stretched behind her. Even Cinder couldn’t help but feel awe at the imposition such a seemingly mundane sight lent Salem. She felt Neo and Emerald tense up near her; they were similarly affected.

The barest ghost of a smile touched the corners of Salem’s mouth as she took in their reaction. “Though born of the pools, the Grimm are animalistic,” she said, lacing her hands in front of her stomach, fingers interlocked. “They take familiar shapes—apes, wolves, bears, serpents, bees. Such creatures are _not_ born of pools of darkness, but rather procreate the _traditional_ way.” Salem laughed, the sound carrying immense weight despite its low volume. “I have long wondered—why should the Grimm be barred from the enjoyment their more feral cousins enjoy?”

Next to Cinder, Emerald’s voice hitched. “The three of us… no, you can’t be serious. You want us to _breed_ Grimm? Personally?”

“Well,” Salem replied smoothly, “you three do have the necessary plumbing, as it were.”

The confirmation sent Cinder reeling. Her? Breed Grimm? Was she really being asked to give her body to these beasts—animalistic creatures of pure destruction? The thought disgusted her!

Or… it should have. Her recent trials against Team RWBY and their allies had left her beaten and humiliated. She still felt the ghosts of old pain, haunting her like mirages, from the scars that infernal brat Ruby Rose had left her.

She wanted to see them beaten. Pushed back. She wanted to see them suffer.

And even the mightiest Huntress would eventually fall before endless waves of Grimm.

Before she could even reflect on what she was doing, she stepped forward. “How productive are we expected to be?” she asked. “A human has one child every nine months. For us three to produce Grimm at that rate wouldn’t make a big difference.”

“A valid question,” Salem replied. “I have modified the Grimm to provide them with relevant equipment for the task. Part of my adjustments mean that any womb which accepts their seed will be transformed. You’ll find yourself with drastically increased fertility and an extremely short gestation time.” Her eyes glittered with promise. “Why… you may find yourself bearing hundreds of Grimm a year.”

_Hundreds of Grimm…_

Cinder pictured Ruby Rose and her devious little teammates swamped by Grimm; she envisioned the satisfaction it would bring knowing that the silver-eyed brat had fallen to one of Cinder’s own offspring.

That knowledge would be worth _anything._

“I’ll do it,” she replied.

From the corner of her eyes, she saw both Neo and Emerald start in surprise—but after a half-minute’s pause, Emerald stepped up. The young woman’s voice was shaky but still resolute. “If—if Cinder is willing, then I am too. I’ll always be ready to follow her.” A split second later, Neo shrugged with a distinct _why the hell not?_ gesture and fell in alongside them.

Salem smiled even wider than ever. “Excellent.”

—

The following day, Cinder found herself in a special breeding chamber created just for her. It was a low, spacious room set aside in Salem’s estate, with windows that showed the land outside and lush, luxurious cushions.

Cinder had abandoned her typical crimson dress, instead dressing in cinnamon-red lingerie. She found herself wondering if the creature before her was enticed by her body—the way her smooth and unblemished skin mottled into the still-scarred remnants of Ruby’s attack on her. Perhaps her Grimm arm would be appealing to the creature?

The beast that was in the room with her— _the creature,_ she realized, _I am expected to mate with_ —was an Ursa. The massive, bearlike Grimm was circling the room, snuffling at her with undisguised interest. Musk was rolling off of it, heavy and humid, and Cinder found, to her not-unwelcome surprise, that her body was reacting. Already she could feel her heart racing, her cunt slickening as her body readied itself to mate with the ursine creature.

It was preparing to bear beastly children.

A lesser woman might have recoiled in disgust or fled in terror, but Cinder Fall was no lesser woman. She knew that the powers she commanded would allow her to carve through this and any dozen creatures with the same effort the wind took to toss an autumn leaf, so there was nothing to fear. And disgust? Any revulsion she might have possessed at the thought of being rutted by an animalistic monster, of being turned into its mate and bearing its young, was offset by the iron satisfaction that the Grimm she bore would help turn the tide of their war on Remnant. All she had to do was imagine Team RWBY and their asinine allies swamped beneath a tide of monsters birthed by Cinder herself, and the ensuing delight made the thought of rutting this beast and birthing its offspring more than palatable.

 _And besides,_ Cinder thought with a surge of appreciation, _it looks like there’ll be something to enjoy on my end after all._ She was thinking, of course, of the Ursa’s cock.

The Grimm, born of dark energy in Salem’s pools, were normally sterile, not possessing any equipment of their own. But Salem’s modifications had corrected that, and _how._ The Ursa now sported an enormous, pink-red erection bobbing between its legs. Its cock was thick and hefty, with an impressive knot at the base. It was far larger than any human cock could have ever been.

At first, the formidable size had left Cinder taken somewhat aback. Was she really expected to lie with such a massive thing? But the more she thought on it, the more certain she became. Salem wouldn’t have chanced harming a womb ready for the production of more Grimm, and besides, Neo was slated to breed with an even bigger Grimm than this Ursa.

By now, having circled and inspected its prospective mate, the Grimm snorted and pawed the ground in approval. Her heart hammering with anticipation, Cinder slowly fell onto her hands and knees, presenting her ass to the Ursa. “Here,” she breathed, reaching back to pull back her lingerie and reveal her flushed and waiting pussy. “It’s all yours.” She could hear the Grimm padding closer. Her breath hitched. This was it. She was going to mate with the Grimm. The first step in her long-anticipated revenge would—

Her voice hitched in a squeal of shock and delight. She spasmed with unanticipated stimuli as the Ursa paid her pussy some attention—not with its cock, but its _tongue_.

It was broad and smooth; for some reason, Cinder had imagined it might have been coarse and rough. The wet heat of the thing was to die for, and she found herself crooning from bliss as the Ursa lapped at her, the regular attentions from its tongue gliding up and down her flushed lips, flying over her clit, and even dipping inside every now and then to make her pant with delight.

“I’m—I’m—hnnnnh, _aah_ —”

Cinder didn’t even know who she talking to. The Grimm? _Herself?_ As the Ursa’s tongue danced over her clit and left her face flushed and her pussy blossoming, she decided it didn’t matter.

For several minutes, she was content to lay there, ass in the air, and receive the beast’s attentions. Cinder Fall—architect of the fall of Beacon, Fall Maiden, right hand to Salem herself—had been reduced to a smitten, cooing mess from being eaten out by a monster.

Eventually, the Ursa left one last luxurious lap around her clit, leaving her panting into the floor of the breeding chamber. _How had the creature known to bring pleasure to me like this?_ Cinder pondered amidst the orgiastic haze. _Could Salem have given it knowledge of how to please human females when she gave it a cock?_ It made a warped kind of sense—the more that women enjoyed sex with Grimm, the more they’d return to them, guaranteeing a higher number of offspring in the long run.

After the last attention paid to her clit, the Ursa dipped its tongue into Cinder, and she arched her back, moaning, as it probed deeper than before. “You’re—p-priming me,” she panted, “you delightful, big, bestial thing…”

The Grimm gave no indication it understood, but when it slipped its tongue out of her with a loud _shlick,_ the ensuing emptiness didn’t have long to last. Its chest rumbling with a pre-mating growl, the Grimm positioned itself above Cinder, its thick cock dragging along the bottom of her belly. She could _smell_ the thing from here, a rough and wild scent even more overpowering and enticing than its musk had been, and she shivered as the Ursa pulled its hips back, dragging its cock along her belly. A small trail of precum glistened on her stomach, left there by the creature’s cock. Finally, the tip teasing her outer folds, Cinder groaned in desperate need, pushing back against the Grimm in a mad attempt to get it to rut her.

And, after a few seconds’ waiting, the Grimm granted her wish.

Though it had paid her a surprising amount of attention with its tongue, the Grimm was still an animal, deep down. And when it fucked, it _fucked_ like an animal. One second Cinder was aching from the burning need of her unoccupied cunt, and the next her voice was keening high into the air as the Grimm thrust into her. Its cock plundered her innermost depths, taking the burning coals of arousal that were filling her loins and turning them into a sizzling inferno of pure lust. She was being stretched hugely, _impossibly._ The creature was taking her so much farther than any human could have ever stretched her.

And all that was just the prelude.

Its growl bubbling into a rippling roar of want, the Ursa began rutting her in earnest. Its hips swung forward and back, plowing its cock into Cinder’s waiting pussy, and the Fall Maiden’s voice arched higher and higher, peaking as her feral mate continued fucking her. Faster and faster the pace went, more and more, _harder,_ and every rut was like a dream. Cinder’s voice cried out high over the chamber. The sheer enormity of the Ursa’s cock was sublime, sending pleasure gusting through her with every thrust.

The weight of the creature’s knot suddenly pressed against her entrance, and Cinder’s voice sang a passionate squeal of delight as it was forced inside, snugly occupying her cunt. The sheer presence of it was enough to push her over the edge—she moaned, cumming, as her tunnel fluttered around the monstrous cock, squeezing and milking it for all it was worth.

And it was worth a _lot._ A growl rippled from the Ursa as its cum flooded into Cinder, filling her womb with a warm and sudden weight and making her blush and bloom with satisfaction. The avalanche of sensations threatened to overwhelm her, and she was content to rest against the breeding chamber floor, her ass held in the air by the Ursa’s knot, as orgasmic bliss rocked through her.

 _That’s it, then,_ she thought with woozy decisiveness. _I’ll bear this creature’s cubs._

Errant footfalls shook her from her reverie. She glanced up, her vision hazy, to see Salem shooting a satisfied look down at her.

“Did you breed well, my Maiden?” Salem purred.

Cinder tried to force out a reaction and was only left shuddering against the floor.

Salem laughed, a small but biting sound, and crouched down to cup Cinder’s face in her palm.

“Good,” she said. “Very, very good.”

—

A mere half-week’s time had passed since the initial session, yet Cinder was already showing.

The Fall Maiden reclined against a cushion, rubbing her gravid belly in wonderment. Salem’s claims about Grimm seed modifying their partners was holding true. Since her breeding session, Cinder had quickly found herself changing. Her already sensual figure had become even curvier as her breasts blossomed with milk to feed her coming cubs, and her hips and ass had plumpened as well in preparation for the long and forthcoming birthing. Her tummy curved beneath her breasts, big enough that Cinder was forced to waddle whenever she moved, usually keeping one hand underneath her belly as she did so. She felt the Grimm within— _my offspring,_ she thought with unanticipated delight—squirming with energy and activity.

In fact, she had forgone wearing any sort of clothes at all. She was changing too rapidly to wear any of her usual attire, and Salem had laughed off her queries as to whether it might be expedient to obtain new ones.

“For what purpose, my little Grimm machine?” she had said, her voice chiding. “You have only to concern yourself with mating. Feel the change come over you… your fertility is in overdrive, and your body will change more and more yet. Embrace your new role as a mother to the forces of darkness.”

Cinder could find no complaint with Salem’s reasoning, and besides: there were other changes more subtle than the ones which were obvious.

Ever since that initial mating, her loins had positively _burned_ with need.

The fire had set in only a few hours after her first coupling with the Ursa, and it had built and built over the day until she was almost consumed with desire. When she’d approached Salem, Cinder’s boss had smiled knowingly at her.

“Why, the animalistic creatures who share their shapes with Grimm often have their females experience cycles of heat to encourage their mating,” Salem had told her. “It seemed fitting to reflect such changes in the Grimm’s human breeders as well.”

“But I—oh, it’s strong, I can barely _think,”_ Cinder had complained, near panting.

“Then why think?” Salem had said, her voice silky. “Go sate your need. It is not as though you will be getting up to much else in your new role.”

And so that night, Cinder—who had (perhaps naively) assumed that she would only lie with Grimm when it was necessary to conceive—found herself rutting with another one, holding close to its musky fur, her voice nearly hoarsening for how she cried out from the creature’s attentions. She had fallen asleep that evening still coupled with it, and when she’d woken the following morning, wincing as the Grimm’s knot popped free of her pussy, she’d noticed with awe that her belly already seemed weightier.

And now, feeling the dual sensations of baby Grimm turning in her womb and her heat throbbing insistently in her nethers, Cinder chuckled to herself. After only a few hours’ rest, it was already time to lie with a Grimm again.

Thankfully, the breeding chamber came with a panel to summon Grimm. Cinder waddled over and pressed it, and before long a horde of Beowolves trotted in, each sporting an insistent crimson cock.

She smirked. Oh, this _was_ going to be fun.

—

Salem strode into Cinder’s breeding chamber, her mouth a terse line. “For what reason have you seen fit to waste my time?”

At the sound of her voice, Cinder groaned, glancing up. “I—I c-can’t—”

“Yes?” Salem said, raising an eyebrow.

“I can’t _move!_ ” Cinder protested, her voice taking a high whine of desperation. Indeed, she had woken this morning to find her belly swollen to such a degree that movement was impossible. She had grown more and more—it was barely over a week since she had first slept with the Ursa!—but on waking this morning, she had found a particularly large growth spurt had beset her the previous evening. She was forced to rest in a reclining sitting position, her arms both splayed behind her to support her weight, her belly so big that it was forcing her legs apart. The scent of sex filled the room as Cinder’s pussy—now almost perpetually flushed with arousal thanks to her heat—pooled some of its own slick beneath it.

“Please, you have to—ohh, _uhhhn,_ hngah! I—they— _uuuhngh…”_ Cinder’s protestations died as her offspring acted up. Their activity was visible as bumps against her skin. Her womb-stretched belly had grown so massive that it rivaled Cinder’s own height.

“I should think that you were rendered immobile,” Salem said, walking forward to trace her finger along Cinder’s taut tummy. She smiled as one particularly active Grimm cub pushed up against her; the sensation left Cinder panting. “Given how fertile I expect you to be, it’s only reasonable that your womb grow to such a size. Indeed, the only concern was how long it took you to get this way.”

“But I—need—to move!” Cinder said, forcing the words out between charged, aroused pants.

“Do you?” Salem rejoined. She rested her cheek and one arm against Cinder’s belly, sighing with delight at the weight of it. “Oh Cinder, why would you ever need to do anything but fuck Grimm and bear their children ever again? Don’t you understand? This is what you _are_ now. A Grimm breeding machine. A factory dedicated to taking monster cock and pumping out their young. This—” Salem rubbed her arms over Cinder’s belly, “—and _these_ —” she reached over to pinch the nipple on one of Cinder’s engorged, melon-sized breasts, making the younger woman gasp as pale milk dribbled out, “—are all that matter. You’re their mate. Their broodmother. Their childbearer. You are a milky breeding bitch, Cinder, and don’t tell me you don’t love it. I can _smell_ your arousal in the air.”

“I—I d-do love it, but—”

“But you want to move? Why?” Salem replied. “I’ll arrange for you to be fed, and the only other thing you need is Grimm cock—and you don’t need to move for _that._ In fact…”

Reaching over, Salem gently but firmly pushed Cinder until the other woman yielded. Cinder laid down, despite knowing that the enormous weight of her belly would make it hard to even sit up again, let alone rise, and soon her entire world became her own towering belly and the two milky breasts in front of it. All else was hidden from view.

But her pussy was more easily accessible in this manner.

“Isn’t that better?” came Salem’s voice. Cinder could no longer see her; all she could take in was her own enormity. “Now the Grimm can sate you whenever you want.” She paused. “Or _they_ want.”

Another sound touched Cinder’s ears—the padding footfalls of a Grimm entering the chamber. She gasped as hairy forepaws grasped either side of her belly and moaned as the Grimm slid into her without preamble.

“Doesn’t that feel good?” Salem asked. Cinder could only whimper a reply, her mind reeling with the energetic thrusts of the Grimm that was dutifully rutting her—and from the high-paced activity of her young, which were more active than ever thanks to the attentions of the older Grimm.

She couldn’t even _see_ the creature that was pleasuring her. It almost made her laugh. But every thrust, every push of the creature’s cock sent wonderment and bliss singing through her, and soon all her worries went away, fucked clear out of her.

 _Salem is right,_ Cinder thought amidst the pleasure. _I’m a baby Grimm machine now. I don’t have to worry about fighting or stress or even movement. All I need is to be satiated._

And as the creature came inside of her and padded away and she heard the sound of _another_ one entering the chamber, she idly reflected that satiation was not anything that would be in short supply.

—

Mere days had passed since her initial immobility, but Cinder had already grown massive. Her belly had tripled in size since them, towering almost to the chamber’s roof and shadowing everything.

Today was the birthing day.

She had expected it to be pained or stressful, but each Ursa cub came easy. No, more than just easy—they stretched her and pleasured her G-spots, bringing her sexual bliss unlike anything she could have anticipated. It seemed that this, too, was part of Salem’s modifications.

Cinder didn’t mind at all. Her joyful gasps and wails filled the breeding chamber as she squeezed out Ursa cub after Ursa cub. Her new young were big, at least a foot at the shoulder already. They needed no assistance to walk, and they beelined straight for their mother’s teats.

Even as she reeled from the incredible pleasure of birthing yet another cub, Cinder glanced up to find more of her young had scrabbled up onto her chest. They were now dutifully nursing away, sucking so vigorously that streams of milk dribbled out of their mouth to trail down Cinder’s tits. Other cubs who had already had their fill curled against the wall or cradled in the shadow of their mother’s massive womb, their little chests rising and falling as they dozed. Their tummies were full of mother’s milk, and each of them sported a little red cock of their own.

Had she known what she was getting into when she’d agreed to be Salem’s Grimm breeder (a decision that seemed a lifetime ago, yet was, impossibly, less than two weeks in the past) Cinder never would have expected the plethora of emotions she’d be feeling right now: a severe determination to bring down Ruby Rose and her other accursed teammates, of course, but also a veritable tsunami of attraction and sexual pleasure—and, yes, even a warm feeling of maternal pride as she considered her beautiful, deadly, mighty, coal-furred offspring.

This was everything Cinder had never known she wanted.

A few hours after the birthing was done and well over a dozen Ursa cubs had been brought into the world, Cinder was left dozing with her offspring—until Salem arrived, leading in another Grimm. This one was a serpentine King Taijitu.

“Let no time go to waste,” Salem told her. “Now that you are finished bearing Grimm, your body is ready to conceive again—no recovery necessary.” Cinder marveled. Salem really _had_ gone out of her way to ensure the most proficient breeding regimen possible.

Cinder spread her legs like a good little breeder, and even as she shuddered with delight at the feeling of the King Taijitu sliding its slender hemipenes into her, she reflected that it felt _right_ to have monster cock in her. The creature’s union with her body felt like nothing less than like it was coming home.

And as her body shook as the serpent rutted her and Salem looked on, pleased, one of the cubs woke and scrambled over to her, crawling up to suckle once again. The milk came smooth and ready, and the feeling of feeding her young brought a sensation of maternal bliss to Cinder, the perfect complement to the way her body was rocking with pleasure.

She was a big, immobile, fertile, milky Grimm machine. She was going to bear so _many_ of their children. And she wouldn’t have it any other way.

**Author's Note:**

> Thanks for reading! Check out my twitter account at https://twitter.com/FestivalGrey. I post updates on future writing there, and also promote story availability in case you want one of your own!


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